Science and Technology Facilities Council
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Astronomers eye evolution of distant galaxies
Astronomers have gained a deeper understanding into galaxy formation in the very early universe. A team of scientists, led by the California institute of Technology (Caltech), in collaboration with Durham University and Cardiff University, have used a technique, originally predicted by Einstein, to show how a young, distant galaxy might evolve to become a present-day system like our Milky Way. The full paper on this research, part funded by the Science and Technology Facilities Council (STFC), was published in the scientific publication Nature, 9 October 2008.
This distant galaxy, which had been identified in the first instance using the Hubble Space Telescope, was observed using the 10 metre Keck telescope on Hawaii, equipped to correct for blurring in the Earth’s atmosphere. Then, using gravity from a foreground galaxy as a zoom lens, this team of scientists was able to see the young star-forming galaxy in the distant universe as it appeared only two billion years after the Big Bang. By coupling the telescope with the gravitational field of the foreground galaxy, a technique known as gravitational lensing, they were able to study the distant star system which lies a billion light years from Earth. This technique, which is the distortion of light rays by massive objects, enlarged the distant galaxy by eight times, allowing the scientists to determine the galaxy’s internal velocity structure and compare it to later star systems such as the Milky Way. The appearance of the foreground galaxy, in the centre of an arc created by the distant galaxy, is similar to that of a human eye, thus it has been officially named the Cosmic Eye.
Dr Dan Stark of Caltech said: “Gravity has effectively provided us with an additional zoom lens, enabling us to study this distant galaxy on scales approaching only a few hundred light years. This is ten times finer sampling than previously. As a result, for the first time we can see that a typical-sized young galaxy is spinning and slowly evolving into a spiral galaxy much like our own Milky Way.”
Durham University’s Dr Mark Swinbank added: “This is the most detailed study there has been of an early galaxy. Effectively we are looking back in time to when the Universe was in its very early stages.”
Data from the Keck Observatory was combined with additional data provided by ESO from the Very Large Telescope at the Paranal Observatory in Chile, and millimetre observations from the Plateau de Bure Interferometer, in the French Alps, which is sensitive to the distribution of cold gas destined to collapse to form stars. The cold gas traced by the millimetre observations shares the rotation shown by the young stars in the Keck observations. The distribution of gas seen at this resolution indicates the gradual build up of a spiral disk with a central nuclear component.
This study provides a glimpse of what astronomers will be able to see in the distant Universe once projects such as the proposed European Extremely Large Telescope, led by ESO - the European Organisation for Astronomical Research in the Southern Hemisphere, come into use.
Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council, which part funded this research said: “This remarkable study is also particularly exciting in that it is indicative of what will be commonly achieved when the next generation of telescopes come on-line. Extremely large telescopes are considered worldwide as one of the highest priorities in ground-based astronomy and STFC is helping to secure the future of the UK in this field through its support for these ambitious astronomy projects, which will enable European scientists to address some of the most fundamental questions in astronomy and physics.”
The following images are downloadable from this web link: http://astro.dur.ac.uk/~ams/CosmicEye/
1) The Cosmic Eye, showing the foreground galaxy in yellow at the centre of the image surrounded by the blue arc of the distant galaxy.
2) A colour schematic of the spinning distant galaxy after correcting for lens distortion. The blue area shows the galaxy moving towards the viewer with the red area furthest away. The
green area is the centre of the galaxy.
3) M-peg clip showing the emergence of the distant galaxy as seen through the Keck observations.
The formation and assembly of a typical star-forming galaxy at redshift z=3, Stark, Daniel, Swinbank, A.Mark et al, Nature, 09 October 2008, vol 455, issue 7214, pp775-777.
Institute of Computational Cosmology: http://www.icc.dur.ac.uk/ Durham University: http://www.dur.ac.uk/
Science & Technology Facilities Council: http://www.scitech.ac.uk/ Royal Astronomical Society: http://www.ras.org.uk/
The Royal Society: http://royalsociety.org/
Wendy Taylor MCIPR
Science and Technology Facilities Council Daresbury Laboratory Daresbury Science & Innovation Campus Daresbury Warrington Cheshire
Tel Number: 01925 603232
Science and Technology Facilities Council The Science and Technology Facilities Council ensures the UK retains its leading place on the world stage by delivering world-class science; accessing and hosting international facilities; developing innovative technologies; and increasing the socio-economic impact of its research through effective knowledge exchange partnerships.
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